Wasp Gives Hope of Controlling New Crop Pest

It’s green, cigar-shaped and smaller than a grain of rice. It also wipes out barley, wheat, oat and rye crops by injecting their leaves with a toxin and sucking out the juice.

Meet the Russian wheat aphid.

The pest has caused an estimated $650 million in economic losses since it entered the United States in 1986 and spread throughout the Midwest and West, according to UC Riverside.

To find a way to control the bugs without using dangerous pesticides, insect expert Dan Gonzalez has traveled to Central Asia, where the Russian wheat aphid originated and where it is kept in check by natural enemies, including parasitic wasps and syrphid fly larvae.

Fly larvae eat the aphids. The wasps lay their eggs inside the aphids, and as the wasp larvae develop, they slowly eat their hosts from the inside out.

Gonzalez released some wasps in aphid-infested areas of California this year. The results were encouraging. He found many “black mummies”--tiny aphid carcasses killed by wasp larvae.

Researchers now want to know if the wasps can survive the winter and disperse with aphids next spring. If so, a natural balance between the wasps and aphids might be reached in two to five years, keeping the pests under control, the university said in a news release.